(1) Field of the Invention
This invention relates to brake shaft bearings.
(2) Prior Art
Semi-trailers and large truck brakes are operated by an "S" cam which is activated by an air cylinder, each cam shaft being supported at its ends by nylon bushes. While the bush at the activating end of the cam shaft can be easily replaced, the bush behind the "S" cam itself can only be replaced by removing the wheels from the axle. On a triaxle trailer, where there are six sets of wheels to be removed, this is not a simple task.
Where the trailers operate off highway, the life of the nylon shaft bushes is drastically reduced as they cannot be lubricated otherwise dust combines with the grease to form an effecting grinding paste. The bushes may wear out as frequently as every three months and must be replaced. As the bushes wear, the cams drop relative to the brake backing plate, causing the bottom brake shoe to rub and wear. Therefore the brake linings have to be replaced more frequently than should be necessary, and wear also occurs on the cam shafts and the bush housing.